1. Field of the Invention
This invention relates to thermal batteries and more specifically to a thermal battery for providing standby or emergency power for a load such as a conventional blowout preventer of a petroleum drilling operation
2. Description of the Related Art
The drilling for oil has always been a hazardous activity for the personnel at the well site, the drilling equipment, and the environment. The uncontrolled release of crude oil and/or natural gas after failure of pressure control systems is known as a blowout. Prior to the invention of pressure control equipment in the early 20th century, an uncontrolled release of crude oil was known as a gusher.
In 1924, the first successful blowout preventer (BOP) was invented. As technology improved, blowouts became relatively rare. Modern blowout preventers comprise a blowout preventer stack, including several blowout preventers of varying type and function and auxiliary components. Blowout preventers are used on surface as wells subsea well including deepwater wells.
A typical sub-sea blowout preventer would include a stack of blowout preventers and associated hydraulic and electrical systems and components. Control of the blowout preventer is typically accomplished in one of four ways. A first way of controlling a blowout preventer is by an electrical control signal from the surface via a control cable. A second way of controlling a blowout preventer is by an acoustical control signal sent from the surface based acoustic signal generator through the water to the blowout preventer. A third way of controlling a blowout preventer is by a remotely operated vehicle (ROV) mechanically operating a control valve to provide hydraulic pressure to the blowout preventer. A forth way of controlling a blowout preventer is by a “dead-man” switch for fail-safe activation in the event of loss of control and power as well as loss of hydraulic lines.
Generally, two control pods are provided for redundant operation. The primary control of the pods is electrical, while acoustical controls, ROV controls and dead-man controls are secondary. An emergency disconnect system (EDS) is designed to disconnect the rig from the well in the event of an emergency. The EDS also triggers the dead-man switch which closes the blowout preventer.
Although blowouts are now rather rare, both the short and long term effects of a sub-sea blowout can be catastrophic. The Deepwater Horizon blowout graphically illustrates the need to further refine blowout preventers and the associated components to achieve total reliability. In the case of the Deepwater Horizon, a document discussed in the Congressional hearings suggested that a battery in the blowout preventers control pod had failed. Several other scenarios have also been proposed to explain the failure of the blowout preventers.
There have been many in the prior art who have attempted to solve these problems with varying degrees of success. None, however, completely satisfies the requirements for a complete solution to the aforesaid problems. The following U.S. patents are attempts of the prior art to solve this problem.
U.S. Pat. No. 3,695,349 to Murman, et al discloses the constriction of a packer or other tool about a pipe string being run in a well altered in such manner while a pipe joint is passing through the packer as to facilitate rapid running of the string in a well and to reduce wear of the packer.
U.S. Pat. No. 4,215,746 to Hallden, et al discloses an electro-pneumatic or electro-hydraulic safety system for shutting in a well or the like in the event of unusual pressure conditions in the production line of the well. The safety system includes a pressure transducer which senses the flow line pressure and provides a corresponding electrical signal to a digital controller. When the signal applied to the controller is outside of a preset range defined between low and high settings of the controller, a control circuit de-energizes a solenoid valve which bleeds fluid from a fluid actuator in order to close a surface safety valve. Once the safety valve has closed, the controller is latched out of service and must be manually reset before the safety valve can be opened. For protection of a subsurface safety valve, the safety system provides a time delay between opening of the subsurface valve and opening of the surface valve and also between closing of the surface valve and closing of the subsurface valve.
U.S. Pat. No. 4,317,557 to On discloses a blowout preventer control system for use in well operations including a blowout preventer having at least one opening chamber and at least one closing chamber, and an operating power fluid source connected to the blowout preventer opening and closing chambers by an opening conduit and a closing conduit, respectively. A valve controlled conduit is connected to the opening conduit to ensure drainage of power fluid from the opening chamber of the blowout preventer. A three-way shuttle valve is connected into the closing conduit close to the blowout preventer. The shuttle valve is provided with an inlet which is connected to the closing conduit and another inlet which is connected by a conduit to an independent blowout preventer operating power fluid source. An outlet of the shuttle valve is connected to the closing chamber of the blowout preventer.
U.S. Pat. No. 4,337,653 to Chauffe discloses a control and recorder system for a blowout preventer for providing a record of operation and status of the various components of the blowout control system at periodic times and after a function operation. The system monitors various functions such as whether the accumulator pump is running, the open and close status of the various rams, bypass, annular, flow line, kill line and choke line as well as various pressures, such as in the annular, the accumulator and the manifold, flow measurements of various fluids in the system and provides alarms for various parameter values. Control and status information may be transmitted through fiber optic cables between various control stations at the rig floor, accumulators and remote locations for avoiding interference by electrical noises or radio frequencies and providing a safety link through hazardous gas areas.
U.S. Pat. No. 4,349,041 to Bates discloses a control valve system and method for blowout preventers having an actuating piston for actuating the closing of the blowout preventer whereby the piston has an opening side and a closing side. The control valve system and method include a means for selectively directing fluid from the opening side of the actuating piston to the closing side of the actuating piston in order to reduce the fluid requirements for closing the blowout preventer and the reduction in stalled horsepower requirements thereby.
U.S. Pat. No. 4,384,612 to Bradford, et al discloses a control apparatus for preventing inadvertent operation of the draw works of a drilling rig upon closure of an associated blowout preventer, the draw works being at least partially operated by air from an air source connected thereto by an air conduit. The control apparatus may comprise control components for connection to the air conduit and movable from a first mode, in which air is permitted to communicate with the draw works through the air conduit, and a second mode, in which air is prevented from communicating with the draw works. Also included are monitor components for connection to the blowout preventer and the control components for sensing whether the blowout preventer is in opened or closed positions and initiating movement of the control components to the second mode upon movement of the blowout preventer to the closed position.
U.S. Pat. No. 4,422,503 to Goans discloses an improved control line blow out preventer valve, having a fluid pressure chamber interposed in a control line extending from a surface control panel to a down-hole safety valve in a subterranean well. Axially spaced inlet and outlet openings are provided in the pressure chamber and a piston is reciprocally mounted between the inlet and outlet openings. A sealing plug carried by the piston cooperates with a seal surrounding the inlet opening. A bypass passage through the piston mounts a check valve which permits free fluid flow in the direction from the control panel to the subsurface safety valve but only a restricted fluid flow in the opposite direction. A check valve is mounted in the outlet passage to prevent fluid flow from the subsurface safety valve to the control panel. A fusible link normally maintains this check valve off its seat so that it does not close until the occurrence of an elevated temperature caused by fire. At the inlet port a bleed valve which is thermally activated is incorporated in order to bleed off the safety valve, or other apparatus, pressure in the event of a fire.
U.S. Pat. No. 5,070,904 to McMahon, Jr., et al discloses a blowout preventer sub-sea control system utilizing hydraulic control of non-critical functions and electro-hydraulic control of selected critical functions, such as the closing mode of one or more shear ram blowout preventers, one or more pipe ram blowout preventers and one or more annular type blowout preventers. In an alternative embodiment, the use of a conductive fluid in a hydraulic hose enables electric signals and hydraulic signals to be transmitted in the same hose.
U.S. Pat. No. 5,398,761 to Reynolds, et al discloses a modular sub-sea control pod assembly having a retrievable pod assembly and a receptacle assembly. The retrievable pod assembly has a stab block and at least one function port having an opening in the stab block. The retrievable pod assembly includes a pod gate which is adapted to move between a first position in which the pod gate covers the function port opening and a second position in which the pod gate does not cover the function port opening. The receptacle assembly includes a receptacle base module adapted to receive the stab block and a receptacle function port adapted to be connected to a blowout preventer hydraulic operator. The receptacle assembly includes a receptacle gate which is adapted to move between a first position in which the receptacle gate covers the receptacle function port opening and a second position in which the receptacle gate does not cover the receptacle function port opening. Seal assemblies are provided to operate with the pod gates and the receptacle gates to seal the function and receptacle function ports against the intrusion of saltwater.
U.S. Pat. No. 6,367,566 to Hill discloses a system and method of the present invention permitting control of down hole fluid pressures during under balanced drilling, tripping of the drill string, and well completion to substantially avoid “killing” of the well and thereby damaging the producing formations in the well bore. The system and method utilizes separate and interconnected fluid pathways for introducing a downwardly flowing hydrodynamic control fluid through one fluid pathway and for removing through the other fluid pathway a commingled fluid formed by mixing of the hydrodynamic control fluid and the well bore fluids flowing upwardly in the well bore.
U.S. Pat. No. 7,062,960 to Couren, et al discloses that the consequences of any failure of a blow out preventer assembly to operate correctly in an emergency can be far reaching. Thus, there is provided an apparatus for registering parameters in the bore of a member which is, in use, connected to a pressurized housing, the apparatus comprising: an electro-control package for attachment, in use, to the member; a test assembly placed, in use, in the member; the electro-control package and the test assembly having means for sending signals to and receiving signals from one another.
U.S. Pat. No. 7,222,674 to Reynolds discloses a distributed function control module adapted for use in a modular blowout preventer stack for use sub-sea comprising a housing, adapted to be manipulated by a remotely operated vehicle (ROV) with a stab portion adapted to be received into a blowout preventer stack control module receiver. Control electronics, adapted to control a predetermined function with respect to the blowout preventer stack are disposed within the housing and connected to one or more controllable devices by a wet mateable connector interface.
Others in the prior art have provided rechargeable batteries for emergency power applications for a variety of electronic equipment. Unfortunately, typical rechargeable batteries do not have an extended shelf life.
Thermal batteries have been used in the past for power sources in many military applications. Thermal batteries are mission critical power sources used extensively for strategic and tactical Department of Defense applications. As such, the reliability of thermal batteries is the highest available for portable power generation sources. Thermal batteries have no self-discharge reactions, and can be activated at any temperature extreme needed (typical test conditions are −54 to +60° C. but can be as high as +80° C.). Thermal batteries also offer extremely high current load capabilities and can be custom fabricated to support any voltage and current requirement. The shelf-life of thermal batteries is over 30 years. Typically a thermal battery outlives the system utilizing the thermal battery.
Therefore, it is an object of the present invention to provide an improved emergency power system incorporating a thermal battery for providing primary or backup emergency power.
Another object of this invention is to provide an improved emergency power system incorporating a single use thermal battery.
Another object of this invention is to provide an improved emergency power system for use in a blowout preventer.
Another object of this invention is to provide an improved emergency power system for extending the useful life of blowout preventer control systems.
Another object of this invention is to provide an improved emergency power system incorporating a thermal battery that may be activated by a control cable.
Another object of this invention is to provide an improved emergency power system incorporating a thermal battery that is activated by an acoustical control signal.
Another object of this invention is to provide an improved emergency power system incorporating a super-capacitor or small rechargeable battery for receiving an acoustical control signal to activate the improved emergency power system.
Another object of this invention is to provide an improved emergency power system incorporating a thermal battery that may be activated by a manipulator arm on a remotely operated vehicle (ROV).
The foregoing has outlined some of the more pertinent objects of the present invention. These objects should be construed as being merely illustrative of some of the more prominent features and applications of the invention. Many other beneficial results can be obtained by modifying the invention within the scope of the invention. Accordingly other objects in a full understanding of the invention may be had by referring to the summary of the invention, the detailed description describing the preferred embodiment in addition to the scope of the invention defined by the claims taken in conjunction with the accompanying drawings.